1. Field of the Invention
The present invention relates to an alarm for detecting radiation and/or air pollutants such as smoke, carbon monoxide, methane, radon or the like.
2. Description of the Related Art
It is known that contamination of detecting circuitry in a smoke alarm or the like, for example by dust or dirt, can occur with the result that the sensitivity of the smoke detection circuitry is compromised. Consequently, it is recommended that such circuitry is replaced on a regular basis, for example every ten years.
A disadvantage associated with existing detectors is that they are often provided with the detection circuitry fixedly mounted to an outer housing as a single integrated unit. Replacement of the detection circuitry therefore necessitates replacement of the entire unit which, as the unit is normally mounted to a room ceiling by means of screws or the like, is often a complicated and time-consuming process.
U.S. Pat. No. 5,280,273 discloses a detector for sensing the presence of a toxic gas having a housing comprising a base and a cover. Detection circuitry is fixed inside the housing and biomimetric sensing material and a battery are contained in a cell which can be inserted and withdrawn from the housing by means of a drawer.
DE 197 33 375 discloses a device for fire detection having a housing comprising a base component and a cover component. The cover component is provided with a printed circuit board fitted with electronic components for fire detection.